After threatening to do so ever since the bicycle tire size drum beat of “bigger is better” started, I finally put the Velocity Dyad wheelset and 28mm wide Continental Gatorskin tires on our Calfee for one of our local loop rides to see if either I or the lovely Ms. Debbie could detect any significant difference compared to our Velocity Deep-Vs with 25mm Vredestein’s. I ran the Gatorskins at 100 psi vs. 120 psi that I’ve been using with the Vredestein’s.
The more important dimension for rims is the inside bead-seat diameter which is 14mm for the Deep V (below left) and 19mm for the Dyad rim (below right). Proportionally, the Dyad w/28mm Gatorskin is actually a better fit than the Deep-V w/25mm Fortezza; a 23mm Fortezza is about ideal for the Deep-V but we stopped using those about 2 years back now.
I’d originally thought that I’d need to change out the True Temper AlphaQ X2 front fork on the Calfee for this little experiment as the forks are only really rated for up to a 25mm tire, but as it turns out there was about 1mm – 2mm of clearance between the tire and fork crown, a good 2mm – 2.5mm at the rear brake bridge and more than enough room with the Campy Record compact caliper brakes.
And the verdict? Well, Debbie didn’t know that I’d changed out the tires and wheels and I’d even made a point of steering the tandem through some sections of broken pavement during the first 10 miles of our ride before asking her, “so, how does the tandem feel?” As usual, her response was a question, “Why. What did you do to it?” I told her that’d I’d changed out the tires and wheels with the wheelset from our Performance Triplet just to see how a larger diameter / higher volume tire might change the feel, handling and performance of our Calfee, which was absolutely true. After explaining the change her answer was a pretty unequivocal, “I can’t really tell that there’s any difference.”
As for me, I could tell that the 28mm tires at 100 psi definitely gave me a more plush-feeling ride, especially on the sections of broken pavement. It was noticeably smoother-rolling on several sections of our route, but interestingly enough… while it felt like the tandem was rolling faster on several sections, a quick check of the speedo revealed the tandem was actually moving along a bit slower than usual. By the end of the ride we were about 5% off our average pace for that particular loop. As for handling, it definitely held a line quite nicely, but it was not as nimble-feeling in the corners, particularly when the bike was heeled-over for two very tight, greater than 45° intersections.
My take away from this little experiment was that, as I suspected… if we lived and rode on surfaces that were not as smooth as our local roads here in the southeast a larger volume tire would definitely be the first thing I’d adopt to improve the comfort of our ride. My guess is, if our roads were not as smooth as they are any loss in performance associated with the larger diameter tire would be off-set by the tire’s ability to soak up bumps and save wear and tear on the riders.
Clearly, this is far from being a definitive test and there weren’t nearly as many controls or repeated events to support a more qualified assessment. But, at least as far as first impressions go, I think we’re good to go with our 25mm tires on Deep-Vs. However, if our roads ever fall into disrepair or if we head back into the land of never-ending chip-seal, expansion joints, or frost-heave-damaged roads we know exactly what to change first.